people, there is also an increase in the zones of disturbance around the towns and villages of the area.
Together with the wet 'hay-lands', once common birds such as the corncrake (Crex crex), the Ballion's crake (Porzana pusilla) and white stork (Ciconia ciconia), or mammals such as the otter, have disappeared from many polder areas (de Jong and Wiggers, 1982). Despite massive government initiatives to protect wetlands, the habitats of meadow- and migratory birds are declining (Bink et al, 1994; RIVM, 1992).
Map 8.2 - The urbanisation of the Amsterdam region between 1930 and 1975
Source: de Jong and Wiggers, 1982
Note: Urban disturbancy zone arbitarily set at 1.5 km in 1930 and 4 km in 1995 to reflect the increased mobility of people